This application is not related to any pending applications.
This application is not referenced in any microfiche appendix.
The invention relates generally to internal combustion engines and more specifically to a replaceable combustion chamber insert for two cycle internal combustion engines.
Improvements to enhance the performance and combustion efficiency of internal combustion engines are well represented in the prior art. For example:
U.S. Pat. No. 1,260,859 issued on Mar. 26, 1918 to A. Bie discloses a cylinder construction for internal combustion engines, and is concerned particularly with the heads thereof, being designed more especially, though not necessarily exclusively, for constant pressure oil engines having their fuel injection valves arranged centrally in the heads.
U.S. Pat. No. 1,914,940 issued on Jun. 20, 1933 to R. Chilton discloses an improvement in cooling internal combustion engine cylinders and associated parts.
U.S. Pat. No. 4,519,359 issued on May 28, 1985 to Ulf Dworak et al and subsequently assigned to Feldmuhle Aktiengesellschaft discloses a mullite plate. In a cylinder head of a piston engine, the surface of the cylinder head facing the combustion chamber is covered by a plate having openings for valves, spark plugs or injection nozzles. The plate consists of mullite containing 2 to 30% of volume of zirconium oxide and/or hafnium oxide embedded therein, plus 0 to 3 mole-percent of oxides of magnesium, calcium or yttrium, with respect to the zirconium and/or hafnium oxide, and of no more than 0.5%, by weight, of other oxidic impurities.
U.S. Pat. No. 4,530,341 issued on Jul. 23, 1985 to Bengt N. J. Palm and subsequently assigned to Saab-Scania Aktiebolag discloses a piston engine having at least one heat-insulated combustion chamber, and parts for said engine. Improved heat insulating of a combustion chamber in an internal combustion engine is a heat-resistant body in at least one surface, which is intended to at least partly limit a combustion chamber. A support body supports the heat-resistant body, said bodies each having facing mantle surfaces. Between said bodies there is a heat-insulating element of a material having a lower coefficient of thermal expansion and a lower modulus of elasticity than the material in either one of said bodies. The bodies and the element are held together at the mantle surfaces by means of a shrink fit.
U.S. Pat. No. 4,562,798 issued on Jan. 7, 1986 to Cornelis J. Van Os and subsequently assigned to Noord-Nederlandsche Machinefabriek B.V. discloses a cylinder head locking construction for cylinders formed or placed in a casing of a motor, in which high working pressures occur. A segmented ring is partially placed in an annular groove formed in the casing of the motor transversely to the axis of the cylinder head. In operation a portion of the ring projecting from the groove rests on an adjacent portion of the cylinder head. A clamping ring is secured around a raised central portion of the cylinder head and presses the segments in the direction of the cylinder head portion, and at the same time prevents radially inward movement of the segments. The segments are pushed inwardly into contact with the clamping ring by a thrust member such as an O-ring.
U.S. Pat. No. 4,630,345 issued on Dec. 23, 1986 to Dieter Lutz and subsequently assigned to SACHS-Systemtechnik GmbH discloses a cylinder unit of a cylinder-piston-combustion engine comprising a cylinder housing and a lining unit inserted into the cylinder housing. The lining unit consists of a cylindrical liner sleeve and a terminal wall and encloses a combustion space. The terminal wall is integral with the liner sleeve. The lining unit is manufactured by a non-cutting manufacturing method like cold impact forming, hot impact forming, deep drawing, tube reshaping, press molding or injection molding.
U.S. Pat. No. 4,646,692 issued on Mar. 3, 1987 to Andreas Deuber et al and subsequently assigned to Alcan Aluminiumwerk Nurnberg GmbH discloses a component for internal combustion engines and a process for its production. The invention concerns components for internal combustion engines with heat resistant combustion chamber inserts, especially components made of light metal with casted porous ceramic inserts positioned by casting around the basic material, in which in order to lower the gas pressure which builds up under the inserts, at least one gas pressure release bore hole is provided in the basic material of the component which leads to the bottom of said insert. The invention further describes a process for the production of these components in which the insert is first fixed in its position relative to the basic element and thereafter the bore holes are produced in the basic material.
U.S. Pat. No. 5,211,153 issued on May 18, 1993 to Minoru Yonekawa et al and subsequently assigned Kloritz Corporation discloses a two-cycle internal combustion gasoline engine cylinder. The two-cycle engine cylinder according to this invention is characterized in that a smooth hard chromium plated layer is formed on a combustion chamber top inner surface of the cylinder.
U.S. Pat. No. 5,361,730 issued on Nov. 8, 1994 to Richard J. Clark et al and subsequently assigned to Clark Industries, Inc. discloses a unitary cylinder head and liner combination is vertically cast as a one piece unit. The liner incorporates a water jacket therein. The water jacket is draftless, allowing water to circulate therethrough more efficiently, increasing cooling capabilities. Such vertical one piece casting is made possible by a novel two piece core which eliminates the need for welding of metal bands onto an outer surface of the liner to produce the water jacket thereof. A novel method of vertical casting is also provided which allows the cylinder head to be cast internal with the liner, allows for increased water capacity in the liner and integral head passages, and allows for a plurality of enlarged air intake channels to be provided.
U.S. Pat. No. 5,586,522 issued on Dec. 24, 1996 to Lawrence R. Phillis et al discloses a cylinder head for an internal combustion engine which includes a replaceable combustion chamber dome and an engine cylinder head housing which receives and supports the combustion chamber dome therein. The dome includes a spark plug housing that fits within an aperture within the engine cylinder head housing in such a way that rotational movement of the dome relative to the housing is prevented. The engine cylinder head housing includes a fluid coolant inlet port, a dome cooling chamber in fluid communication with the inlet port and which surrounds an outer periphery of the dome, and an exhaust port in fluid communication with the dome cooling chamber whereby coolant is directed to a cylinder block for the engine. The housing further includes a cylinder head housing cooling chamber in fluid communication with coolant within the cylinder block, and an outlet port in fluid communication with the cylinder head housing cooling chamber.
As can be clearly distinguished from the instant invention the ""522 patent cannot be practiced absent specifically tooled surfaces which allow for a complimenting locking mechanism to prevent rotational movement of the ""522""s replaceable dome (See column 2, lines 30-44).
U.S. Pat. No. 5,657,729 issued on Aug. 19, 1997 to Steven Atmur et al and subsequently assigned to Northrop Grumman Corporation discloses a ceramic cylinder head or cylinder head liner for an internal combustion engine. The cylinder head is made of a fiber reinforced ceramic matrix composite material and includes a heat sink on the top surface to keep touch temperatures at a reasonable level. The preferred embodiment employs water cooling so as to reduce engine compartment temperatures and provide a supply of hot water for passenger compartment heating.
This invention relates generally to internal combustion engines of the two cycle design. More specifically, the present invention relates to a tunable replaceable combustion chamber insert supported within a fluid-cooled housing.
Two cycle internal combustion engines are characterized by one or more cylinders consisting essentially of cylindrical bores within an engine or cylinder block. A piston fits within the cylinder such that it can move reciprocally. One end of the cylinder is closed by a cylinder head to establish a combustion chamber between the top of the piston and the cylinder head. The two cycle cylinder construction differs from four-cycle cylinder construction in that the latter incorporates intake and exhaust valves in the cylinder head while the two cycle engine has intake and exhaust ports in the wall of the cylinder.
When the piston is reciprocated to its lowest position in the cylinder, the maximum volume of the cylinder is defined. The minimum cylinder volume is defined when the piston is at its highest position in the cylinder. The ratio of maximum volume to minimum volume is referred to as compression ratio. The greater the compression ratio, the more efficient the engine. In most internal combustion engines, the cylinder head is manufactured with a shaped pocket or chamber which defines the cylinder volume at the highest piston position and therefore directly affects the performance of the engine.
While combustion chamber definition is the single most important function of the cylinder head, the cylinder head also serves to dissipate heat generated by the combustion process. For this reason, water-cooled cylinder heads are generally manufactured in two sections by machining or the like.
There are many applications which require changes in cylinder head design. Such changes may be necessitated not only by a need to vary engine compression ratio but also to adapt an engine for different octane rated fuels or for different fuels. In particular, it is common practice to modify cylinder heads in order to develop high performance engines. In some situations, such as racing, it is often desirable to be able to modify a cylinder head to obtain a performance characteristic suitable for immediate conditions.
Aftermarket cylinder heads are typically manufactured with either integrated combustion chambers as part of the cylinder head itself, or with replaceable combustion chambers. In the case of cylinder heads utilizing replaceable combustion chambers, several problems presently exist. In particular, such combustion chambers do not typically provide adequate cooling to both the cylinder head housing and the replaceable combustion chamber, are not easily modified for changes in different fuels or octane ratings and changes in weather conditions, and they often rotate during spark plug installation and/or removal.
By way of illustration, if during a touring trip a spark plug requires replacement and during that operation it is discovered that the replaceable combustion chamber insert turns without the spark plug being removed, the engine is unable to be operated further. It must be taken to a location where the cylinder head may be removed. The problem is exacerbated during a racing event where the spark plugs must be removed and replaced several times. If such rotation of the combustion chamber insert occurs, the cylinder head must be removed, which could limit a racer""s ability to arrive at the starting line on time. While this problem has been described by the prior art in U.S. Pat. No. 5,586,522, the ""522 patent""s xe2x80x9cdomexe2x80x9d requires an interlocking means to secure said dome within a uniquely calibrated and interlocking cylinder head can be very costly and complicated to manufacture.
With regard to the problem of adequately cooling the cylinder head and, particularly, the replaceable combustion chamber, typical cylinder head cooling/flow design does not allow for the distinct flow of coolant therethrough in a plurality of flow paths at different temperatures. Thus, the different cooling requirements of the cylinder head in contrast with that of the replaceable combustion chambers are not specifically addressed.
Accordingly, there has been a need for an improved cylinder head for an internal combustion two cycle engine wherein the replaceable combustion chamber can be easily changed according to atmospheric conditions and different fuel or octane ratings for high performance racing and wherein the replaceable combustion chamber insert can be easily and economically machined to prevent rotation during installation/removal of the spark plug. Additionally, there exists a need for a novel replaceable combustion chamber design in which the cross section is uniform in thickness to promote the optimum heat transfer from the effect of the coolant. The present invention fulfills these needs and provides other related advantages.
This invention involves a new method of securing a combustion chamber insert into a water-cooled cylinder head without rotating the insert during installation or removal of the spark plug. The combustion chamber of the instant invention is also tunable for optimum performance in various atmospheric conditions and differing fuel octane ratings. The invention can be practiced on any water-cooled two cycle internal combustion engine, such as a motorcycle, snow mobile, go kart, and other forms of two cycle internal combustion engines and is machined from a single aluminum billet inserted into a cylinder head cover that is water-cooled. The combustion chamber insert may have different combustion chamber volumes for fuel octane rating and atmospheric conditions.
Consequently an objective of the instant invention is to provide a replaceable combustion chamber insert supported within a fluid-cooled housing.
Another objective of the instant invention is to provide an insert allowing for the varying of engine compression ratios.
Yet another objective of the instant invention is to adapt an engine for different octane rated fuels or for different fuels.
A further objective of the instant invention is to modify a cylinder head to obtain a performance characteristic suitable for immediate conditions.
It is an objective of the instant invention to provide for adequate cooling to both the cylinder head housing and the replaceable combustion chamber.
Another objective of the instant invention is to provide an insert which avoids the rotation problems during spark plug installation and/or removal of inserts and cylinder heads associated with the present art.
Yet another object of the instant invention is to allow for the distinct flow of coolant through a replaceable combustion chamber in a plurality of flow paths at their different temperatures.
A further objective of the instant invention is to provide for a novel replaceable combustion chamber design in which the cross-section is uniform in thickness to promote optimum heat transfer precipitated by an engine coolant.